Perhaps you should try some spelling variations:
thiet tach » chiet tach, thien hach, thuat tach
hoc thiet » hoc thieu, hoc thuyet, hoc hien
nang sang » nang song, nong san
dung cong » dung trong
sang ma » tang ma, nang ma, sang tao
ma dung » mai dung, m dung, va dung
tan ran » tan tran, tan san, tan rao
tan van » tran van, tang van, luan van

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: hoc thiet tach - nang sang ma dung cong ((tan ran) or (tan van)) cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc thiet tach - nang sang ma dung cong ((tan ran) OR (tan van)) cau.
• Adding a wildcard symbol may retrieve word variants: hoc thiet tach - nang sang ma dung cong ((tan ran) or (tan van)) cau*.